


Being the First

by Lalaen



Series: Alpha/beta/omega Verse [1]
Category: Shingeki no Kyojin | Attack on Titan
Genre: Alpha/Beta/Omega Dynamics, Biting, Claiming, First Time, Knotting, M/M, Marking, Mating Cycles/In Heat, Mating Rituals, Omega Verse, Scent Marking, Scenting, help do i need to tag this anything else, scruffing
Language: English
Status: Completed
Published: 2014-02-03
Updated: 2014-02-03
Packaged: 2018-01-11 00:19:05
Rating: Mature
Warnings: Underage
Chapters: 1
Words: 4,343
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1166347
Author URL: https://archiveofourown.org/users/Lalaen/pseuds/Lalaen
Summary: <blockquote class="userstuff">
              <p>Since Reiner and Bertholdt are the oldest boys in 104th, maybe it isn't surprising that Bertholdt is the first omega to go into heat.</p><p>He'd always thought he was too tall to be an omega.</p><p>(No mpreg or risk of pregnancy)</p>
            </blockquote>





	Being the First

**Author's Note:**

> basically i wanted to write some stuff for this trope that wasn't personality erasing or all about mpreg or BOTH because there is an extreme lack of that
> 
> yes there will be more ficlets yes i am sorry

Hot.

Really, really hot.

It was the first thing Bertholdt noticed when he woke up, that he was drenched in sweat with his sheet clinging all over him. The second thing, which dawned on him with growing horror, was that he must've had a wet dream. There was… a rather sizeable sticky spot in his pants, and his dick was still hard. He knew his face must be burning red, but he was already so warm that he couldn't feel it. Sweat actually dripped down his back.

Then he noticed Reiner was incredibly close. His short hair was tickling the back of Bertholdt's neck, and he found that bizarrely overstimulating. He almost moved away, but honestly, that suddenly felt like a very difficult thing to do. 

As much as he'd love to lay here and die of embarrassment, he knew that for the least possible humiliation he did need to tell Reiner. He blindly reached behind him, smacking at the other boy because it was honestly the only way to get him awake. As he twisted to do so, he noticed his neck was stiff - though seeing as he slept in some pretty ridiculous ways, that might not be so abnormal.

"Mmn?" The blond nuzzled closer, and he almost jumped away in response. Fuck, his nerves were jangling. Anxiety clutched at his stomach as he worried there might be something wrong with him. Flu? He'd never had one that made him so hypersensitive.

"Uh, I. Need new pants," he muttered under his breath. He'd be more humiliated if he hadn't done the same thing for Reiner a few times. Regardless, he got treated to a soft, sleepy chuckle. 

"Yeah, okay." Reiner shifted to push himself up, but paused to sniff audibly at where his neck met his jaw. "… you smell good." 

Something about that made a thrill shoot down Bertholdt's spine, and when his groin throbbed he almost gasped from sheer surprise. Fortunately, since it was only his best friend he didn't have to formulate a response and could just lay there being red and sweating himself to death and trying to will his inconvenient hard-on away. Once he managed to put on the clean pants, he quietly and awkwardly slipped off to have a cold shower before too many of the other boys got up.

Soon enough, he was joined by the rest of the boys of 104. When Reiner casually sauntered in naked - a sight he was more than used to - he immediately had to turn away and lower the temperature on his shower just to be safe. What the hell was his problem?

Bertholdt trailed behind the others, towel around his thin waist. He felt more anxious than usual about not being able to get near sociable Reiner. Normally, he just felt safer and more calm with his friend near; but now he could feel a physical pain that there were people between them. He told himself that it must just be because he was feeling strange; as he did get anxious very easily.

"Bertl, what's the matter? You've gotta get ready for breakfast." Reiner placed a gentle hand on his shoulder, obviously having noticed he was just sitting there. At the very word 'breakfast', Bertholdt's stomach churned and he had to force himself to swallow. He must've gone pale, because his friend suddenly looked more worried. 

"I. Don't think I should go," he managed after a moment, still very queasy. 

He clearly didn't need any more explanation, able to see that his friend was not feeling well. "… I'll get you up so you have enough time to get ready."

Nodding, Bertholdt climbed wearily back up to the top bunk and ignored the pang he felt when Reiner left the room. He was too old for sentimental shit like needing his best friend around when he felt sick.

By the time breakfast was over, his abdomen was wracked with painful cramps and he could barely control his violent shaking. Now he was genuinely a little scared. He might suspect food poisoning, but with all of them eating at mess every day he'd surely not be the only one stricken. He was in enough distress to not really care any more if it was childish to want Reiner there, so he tried to focus on suffering through the moments until his friend would be back. It'd be okay if Reiner was here. Something deep in the pit of him was telling him that.

Bertholdt could hear Reiner's loud voice as he chatted with Connie on the way in the room, and weakly lifted his head. A moment later, his friend was peeking up at him over the top of the ladder, letting out a low whistle.

"You look like fucking shit."

"Thanks," Bertholdt mumbled. He was doing everything he could to resist crawling closer, the need to touch Reiner was overwhelming and he honestly felt too terrible to worry about why.

It suddenly occurred to him that the blond smelled absolutely amazing. So amazing that it was making his stomach tighten in strange ways.

"Stay here, okay? If Shadis whines about it I'll kick his ass." The tone of Reiner's voice was making him a little dizzy. He just nodded helplessly, wishing his friend would come close and oh god, kiss him? Hold him? He knew it wasn't going to happen, Reiner had never been quite that casual with his affections - and any time but now, Bertholdt was very glad for that.

"Is he feeling better?" Came the sound of Armin's voice from below. Reiner's head snapped around frighteningly fast, his expression hardening from soft concern into annoyance. 

"No." It came out rough and growly and wow, that sure was enough to get him turned on.

How could he possibly be getting turned on when he felt this awful? From what he'd gleaned from his other, apparently shameless classmates; he was less sexual than most. The symptoms were strange enough already without -

Oh.

Oh no. Oh please no. 

Bertholdt rolled over, burying his face in the pillow. This couldn't be happening. 

He couldn't be an omega.

He was already too tall, for one thing. There had to be another explanation. He should be, must be just another beta. He tried to ignore how absolutely impossible it was to ignore the way Reiner smelled, even from across the room. He kept his face buried deep in the pillow, as deep as he could while still breathing, and tried to focus on how his sweats were getting worse again rather than how when Reiner left the room again it felt like someone had scooped out his insides.

Half of him desperately wanted Reiner to come back and make it better, the other half was terrified of his friend even finding out. He curled in the sweat-damp blankets and tried to ignore the fact that his arousal was not going away.

Time started to blur a little, but before a few hours had passed he'd given in and touched himself. The resulting wet mess made what he was absolutely undeniable, and it didn't even get rid of that tight discomfort in his stomach. All it did was overwhelm him with shame and frustrate him so much he was almost shaking.

Bertholdt fell into a light and unsatisfying sleep soon after that.

He woke up to a deep snarl that he felt through his entire being. It made his groin actually throb, and before he had even gained awareness he found himself whispering "Alpha."

He'd never thought about it, never considered Reiner's inclination, but at that moment it felt so incredibly right, he knew without a doubt it was true.

Even though the word had been so quiet, Reiner reacted. A hand went immediately to Bertholdt's head, stroking through his hair possessively. Apparently that was all his body wanted, as he immediately felt himself start to relax. What he now instinctively recognized as the alpha scent was completely overwhelming, making him dizzy and unable to think about anything other than how turned on he was.

"Back the fuck up, Bodt. Don't even look at him." Reiner's voice was a husky growl that made him shiver.

"Calm your tits, Reiner. He's just trying to help." 

"Jean, no," that was Armin's voice. Bertholdt felt a pang entirely different from the agonizing ache he felt for Reiner; more just a feeling that he'd be fine with him being near. "I think he might've triggered Reiner's heat too. Can't you smell him? Obviously he's going to be protective."

Reiner was still stroking his hair firmly, and Bertholdt pushed himself up weakly to crawl closer and let himself fall partially on the Alpha's lap. For probably the first time, he didn't give a shit that there were people around. He pressed his face into Reiner's thigh, then shifted just a little to inhale deeply from his crotch. It pushed him to the point of mindlessness, and he barely noticed Reiner's surprised gasp. He found himself reaching down with a shaky hand to touch himself, and made no effort to stop it. There was a growing wet patch on the front of his pants. Fortunately, since they were on the top bunk, no one could see.

"Should we tell Shadis that neither of them are coming?" that was Eren. He knew they must've been going back for after-lunch training, but couldn't manage to think about it much more.

"… I doubt Reiner would leave him." Marco? Marco. He smelled good. "And I'm pretty sure omegas can't do anything when they're in heat."

"Should we let someone know about this?" The tiny part of Bertholdt's mind that still saw reason recoiled at that thought. He was still ashamed when he realized that it was him they were referring to as _omega_. 

"… I'm not leaving." Reiner said slowly, like he had to put effort into thinking clearly. His voice wasn't that thrilling growl any more; in fact he sounded quite normal, but his hand tightened in Bertholdt's hair. "I… don't think you need to tell anyone. Bertl's fine. He has me." 

Bertholdt's stomach tightened at the words. He and Reiner had shared a fair few kisses, sure, and had no qualms about cuddling together in bed, but they'd never talked about what they might or might not be.

Reiner seemed much steadier now, far less feral. They must've startled him somehow, and since this was his first heat too he couldn't control his protective urges very well. His heavy hand went back to stroking Bertholdt's hair.

"Sorry for snapping like that. Just… try and stay the fuck back."

"… you sure you can handle this, man?"

"Yeah," he sounded a little breathless. "I've got it." Bertholdt was only conscious of the hand on his head. There were a few murmurs, but he got the sense that the other boys were filtering out of the room. The air was thick with tension, and he couldn't help but squirm against his own hand.

Suddenly, Reiner scooped him up and tossed him back onto the bunk proper. When Bertholdt caught a glance of his face, his breath caught in his throat. It wasn't that Reiner looked particularly fierce, but his jaw was set in a stern line. "Fuck," the word was a soft growl. "I'll try not to lose myself, but no promises." He leaned down, rubbing his face roughly into Bertholdt's neck, marking him with his scent. 

Then he pulled back, taking the omega's face in both of his large hands and giving him an intense, piercing look. "Don't… be afraid, Bertl. I'm going to claim you. You want that?" Bertholdt found himself nodding almost frantically, and he'd be embarrassed if it was anyone else.

He was still embarrassed. Oh my god, was he ever. Later he'd be humiliated by how much he'd wanted it, by how eager he was; but right now he just _wanted_ …

What did he want? He didn't have enough experience with this feeling to know, but he wanted very much.

Reiner had let him go only to pin him back to the bed by his shoulders, something that yet again went straight to his dick. In fact, he could hardly hold back a gasp. The blond pushed his shirt up roughly, nuzzling into his stomach in a way that probably would have tickled normally and inhaling audibly, nose pressed against his skin. 

"You smell fucking amazing," he said, a deeper and huskier tone in his voice than Bertholdt had ever heard there. He looked up at the omega - his omega - with lust burning in his dark eyes. "I'm… going to knot you, Bertl." He breathed, tongue darting out to trace hungrily along the thin line of hair leading down to the band of his pants.

Those words actually made Bertholdt squirm, no longer having any ability to cope with how incredibly aroused he was. "Please," he managed to whisper. He was literally aching inside. The hand that he was using to restlessly palm himself kept wanting to slip back just so he could have something filling him, anything; his body kept clenching on nothing and it was pain. He wasn't that far gone, not yet. "Please, hurry… fast, now. Please just do it fast." He panted, face bright red. He had no presence of mind to be embarrassed about how eager and needy he was. Not now.

A little growl came from Reiner's throat, and he latched down hard on Bertholdt's hip with his teeth. The omega tried to kick his legs, find some way to express the overwhelming sensations in his body, but his heavy partner was effectively pinning them to the bed. 

"You need me?" Reiner said in that husky voice as he crawled back up to cover him completely. This time, though, his hand was shoved in between then. His eyes were bright as he asked. Bertholdt thought it was very obvious that he needed him, furthermore, he always needed him and always had, but evidently he wanted to hear it.

"Y-yes," he gasped as Reiner's hand wrapped around his dick. "Yes, I need you, I need you _right now_." His voice rose in an uncharacteristic high whine, an absolutely unheard of resolve behind his words.

Reiner actually made a choked sound, curling his back up and biting almost viciously at Bertholdt's neck. It hurt, but it was an incredible hurt. He could literally feel the endorphins rushing through his system, released by the alpha's teeth clutching at the gland there. No wonder his neck had been so stiff. He actually mewled, pawing helplessly at Reiner's back. He wanted to beg more, wanted to do anything to get his alpha inside him right now, but his voice wouldn't even work. He just chanted please, please in his head over and over again, hoping it would come across. He could feel his dick leaking all over Reiner's hand, the friction only serving to frustrate him more and giving him no relief. 

Briefly letting go so he could reposition himself, Reiner murmured a quick 'shh' that was half growl before latching on to a slightly different spot on Bertholdt's neck. He practically ripped down the thin pants, and as soon as his hand slid back the omega's hips curled up encouragingly. Yes, yes, _please_ …

Despite having never done it before, Bertholdt's eagerness let one finger slide in with ease. He gasped and whined and his body clutched needily; begging for more. Somewhere in the back of his mind, he knew that normally he would not be the case - that surely nerves would make him tight. As it was, he took another thick finger almost immediately. The stretch didn't even hurt, just felt strange and… good. He clung to Reiner's strong back, panting heavily, resting his chin on the alpha's cheek as his neck was sucked and bit. It was fortunate that everyone would except him to have heavy bruising there, though it would mark him as an omega to the entire division and supervisors alike.

He'd be humiliated later. Now, his brain buzzed with unbearable pleasure as Reiner scissored his fingers. He was panting too, drooling on Bertholdt's neck, audibly smelling his skin. The omega's heart almost stopped when he pulled his hand back; clearly not wanting to waste any more time when his partner was so eager and ready.

It seemed like the anticipation of waiting for Reiner to mount him lasted forever, though it was probably only seconds while the alpha slicked himself and got in position. Bertholdt felt a physical pang at the realization that while inside him, Reiner was not going to be able to reach his neck with his teeth. However, there was not much time for that. Soon there was pressure as Reiner's back curled, and he did his very best to welcome the intrusion.

All at once, the pressure gave way to a stretch and a slide that even his heat couldn't mask the pain of. A small, strangled sound came out of him, and Reiner looked up with lust-darkened; but still very lucid eyes. "You okay?" he rasped, and Bertholdt paused before giving a slow nod. There was still a strong, burning pressure, but every fibre of his stupid omega being was aching to be knotted, to be joined with an alpha - his alpha - an unstoppable biological urge left over from when omegas could actually bear children. 

Reiner seemed to know he had to slow down. He waited a moment, hands firm on Bertholdt's sides, before continuing with a much slower press of his hips. "I have to get all the way in before my knot's up," he managed, his voice rough and husky, color high on his cheeks, "or I'm not getting in."

Bertholdt nodded again, hooking a shaking leg around Reiner's waist. As soon as he felt the increase in size, he somehow found the self control to snap his hips back.

They tied with a pop. Reiner grunted, fingers tightening on his hips enough to leave bruises. Bertholdt couldn't stop a hot gasp, thighs twitching. Now that the alpha was inside, he seemed huge. It still stung, but he was already getting used to it; and being so full was satisfying in a way he didn't even think possible. 

"Mine," Reiner breathed against his ear, voice now nothing but a low growl. Bertholdt actually felt his eyes roll back in his head; almost coming to climax from the word alone. He felt another spurt of precum hit his abdomen, felt the warm and calming crush of Reiner above him, felt the swell of the knot stretching him.

"Alpha," he whispered, his throat still barely working. Reiner rested his chin on Bertholdt's sternum, looking up at him with predatory, possessive lust in his eyes. He slowly rocked his hips, the knot making him unable to thrust. Fortunately that didn't matter. Every little movement pushed on something deep inside Bertholdt that he'd never felt before; making him go white and numb with pleasure. 

He might have actually screamed as he finally got off; but everything went so blank that he wouldn't know if he did. He came to breathing heavily with his head back against the bed, struggling to catch his breath but enjoying the closest thing to a clear head he'd had in a while. "Reiner," he managed to whisper, trying to lift his head properly to look at him. 

"Mn?" Reiner's weight was resting on him fully. They were still tied, of course, and Bertholdt squirmed a little to get comfortable. Being so full didn't feel as good any more, thought it didn't feel bad either. It was still satisfying, and he felt like it was keeping back the stomach cramps from earlier. "I too heavy?"

"No." Bertholdt mumbled back. "Nice." He reached down with a shaking hand, resting it on Reiner's shoulder. He felt safe underneath him, safe and protected and at peace. He didn't have to worry about being an omega, or what anyone else would think of him, or that he'd just done a whole host of embarrassing things.

His alpha was here.

They broke their tie within the next half an hour, and Bertholdt's heat made him needy again as soon as he was empty. Reiner obliged by filling him back up with fingers until he was ready to knot again, which fortunately due to his own heat was not long at all.

By the time dinner was over and the rest of the boys were coming back to the dorm, Bertholdt's neck and shoulders were marked up darkly with bruises from Reiner's teeth. They'd coupled many times, enough that he was starting to feel sore and somewhat sated, enough that he knew he'd really ache when his heat was gone.

They were tied again when the other guys started coming back in, and the temporary reprieve had restored just enough of Bertholdt's mind that he started squirming with embarrassment. Of course he was stuck fast, but Reiner threw the sheet over them to maintain their modesty and tried to soothe him by running a hand down his side. The alpha was utterly unashamed, but Bertholdt dragged a pillow over to bury his face in. He absolutely did not want to see anyone right now.

"You gonna keep us up all night?" That was Jean's brusque voice.

Reiner chuckled, chest brushing against his partner's back. "Wait till it's your turn, Kirschstien. I'll get you back."

"Looks like you did a number on him," That was Eren, and he seemed to have considerably better humor about the whole thing. Bertholdt shrunk in on himself when he realized he was being looked at. When he forced his dizzy mind to think about it, he probably did look pretty bad. His neck felt swollen with bruises. "We brought a little food and water for you two. You gonna bite my head off if I come over there?"

Reiner chuckled again, but the calming hand on Bertholdt's side slid down to become a possessive arm around his waist. "Don't know if I can make any promises."

"I'll do it." Armin sounded pretty confidant, and Bertholdt supposed it was for good reason because Reiner tensed no further as he heard the other boy climbing the ladder.

"Thanks," the alpha grunted, leaning over his partner. Bertholdt tried to sink down smaller.

He was not hungry at all, but Reiner made him choke down a bit of bread and take a glass of water. When night came, they could both only manage a scant few hours of sleep before waking up for more frenzied mating. It was exhausting - in fact, one of the times Bertholdt wasn't even sure if he'd ever properly woken up, or if it even happened at all. It could just be a dream brought on by his heat to keep him from resting even when he was asleep.

He did remember hearing Eren mumble something about "all these fucking pheromones making me horny", but he might've dreamed that too.

It wasn't until some time in the middle of the next night that he finally, exhaustedly pushed Reiner's fingers away as they sought to keep him full until they could tie again. His entire core ached, centred on a keening pain that was the spot which had once brought him such pleasure. Overstimulation was a disgusting understatement. His entire body shook; now not because he needed release but because his every muscle was screaming for sleep, for everything to just stop. The cramps in his stomach had subsided for a bruised feeling that he did not doubt stemmed from the constant pounding his insides had just endured.

"Are you done?" Reiner sounded completely breathless and a little hopeful. 

Bertholdt managed to return a sluggish nod. 

"Thank fuck, I was really starting to chafe. Get some sleep, okay? I think we earned it."

He couldn't even keep his eyes open. He told his head to nod again, but the effort it would take to make it actually happen seemed enormous. He was becoming mildly aware of how disgusting he was - how his hair was greasy with sweat, how his thighs and ass were all but caked in Reiner's leavings. He was numbly conscious of the horrible slimy mess inside of him, and only too conscious of the stickiness coating what felt like his entire front from the lubrication his body had forced itself to produce. That was even ignoring how filthy the sheets were with bodily fluids.

However, he was already half asleep, and it seemed impossible to regard these things with anything but the mildest interest.

When he woke up, he realized he didn't remember falling asleep. He also realized he was laying in Reiner's bed, which was almost completely clean, as compared to his which they'd despoiled.

That led to the further realization that he was a lot cleaner than he had been before. His hair still desperately needed a shower, but it seemed like he'd been wiped clean; even the disaster inside of him seemed somewhat lessened. He felt sure that he owed this to Reiner, who was pressed up against him and sleeping like a log.

His mate. 

He tried the title out now that he had a clear head, and felt heat flare in his cheeks. No one seemed surprised at this development, and that might be the most embarrassing of all.

Was he even surprised himself? He certainly wasn't surprised that Reiner was an alpha, as much as he hadn't put much thought into it. He somehow doubted that the blond was surprised that his best friend was an omega, either, as looking back he'd always been extremely protective.

Bertholdt let out an audible sigh, rolling over and pressing his face into Reiner's shoulder. He'd think about it later. He was sure to have a vicious limp for days, and between that and the dark bruising all over his neck he was certain he wouldn't be able to stop thinking about it.

That was even ignoring all the looks he was going to get.

Ugh.

**Author's Note:**

> i am so sorry i have never been so sorry


End file.
